Originally Posted by scottydl
Lately while locking w/ keyless entry (or just tooting my horn for the fun of it), I've noticed I sometimes only get a single horn tone. I know it should be a standard double-tone horn, and I have heard it from my car before.
Um, not exactly: you don't have a "double-tone" horn; you have two horns, each of which blows a different note. Apparently one of them isn't tooting anymore.
You'll need to locate them under the hood; they'll probably be mounted close to one another, and (I think) the horn wire is green. They may be a little hard to see, so have someone you trust honk the horns for you while you home in on where the surviving honk is coming from. (I say "someone you trust" because you don't want the twit giving you another blast while you've got your head under the hood and close to something greasy/heavy/pointed/etc., which would then require you to take time out from your Horn Repair project to murder your assistant, bury the body in the backyard, etc.)
You may be able to turn its adjustment screw _slightly_ one way or another to improve its honkability, but generally speaking, once they start failing on you, they're usually toast.
The musical note that the horn blows will be plainly cast into the housing as a single capital letter by itself: "A", "C", "E" or "F" are the most common, although I have an idea that most every note in the octave has been produced by AC-Delco at some point in time, and big old Buicks in particular tend to have sets of four under their hoods, so have fun mixing and matching to get the chord you want to hear. Just be sure to install the horn with its opening pointing downwards for rainwater drainage.